Some may have noticed that the EFF has warnings [NB: https://www.eff.org/deeplinks/2018/05/attention-pgp-users-new-vulnerabilities-require-you-take-action-now] about the use of PGP out which I consider pretty overblown. The GnuPG team was not contacted by the researchers but I got access to version of the paper [NB: https://efail.de/] related to KMail. It seems to be the complete paper with just the names of the other MUAs redacted. Here is a response I wrote on the weekend to a reporter who inquired on this problem: The topic of that paper is that HTML is used as a back channel to create an oracle for modified encrypted mails. It is long known that HTML mails and in particular external links like <img href="tla.org/TAG"/> are evil if the MUA actually honors them (which many meanwhile seem to do again; see all these newsletters). Due to broken MIME parsers a bunch of MUAs seem to concatenate decrypted HTML mime parts which makes it easy to plant such HTML snippets. There are two ways to mitigate this attack: - Don't use HTML mails. Or if you really need to read them use a proper MIME parser and disallow any access to external links, - Use authenticated encryption. The latter is actually easy for OpenPGP because we started to use authenticated encryption (AE) since 2000 or 2001. Our AE is called MDC (Modification detection code) and was back then introduced for a very similar attack [NB: Massive Fail der gesamten in- und ausländischen Presse & inkl. EFF].
gnupg-users mailinglist, 14.05.2018